Problems creating .h5p archive

Hi,

I am trying to automate content creation based on external information. I need to "unzip" the .h5p archive, alter content.json and "re-zip" the folders and files.

I am running into quiet some trouble as the "re-zipped" content causes an error when trying to upload it to h5p.org. 

I get the following error:

File "content/" not allowed. Only files with the following extensions are allowed: json png jpg jpeg gif bmp tif tiff eot ttf woff otf webm mp4 ogg mp3 txt pdf rtf doc docx xls xlsx ppt pptx odt ods odp csv diff patch swf md woff2 wav vtt webvtt gltf glb.

I tried zipping with 7zip, with the built in windows tools and also on linux with the "zip" utility but I run into the same problem. I tried to preserve the file structure but obviously am failing at that.

What is the right way to create .h5p archives from unzipped .h5p archives?

Thanks